Hierarchical Dictionary with Statistical Filtering Based on Word Frequency

2. The method of claim 1, wherein the first data structure, the second data structure, and the third data structure form layers of a data structure, each of the layers comprising a fixed size hash map that is associated with a different capacity limit, a different frequency limit, and a different period of time from one another among the plurality of words.

3. The method of claim 1, wherein each of the first data structure, the second data structure, and the third data structure are independent dictionaries.

5. The method of claim 1, wherein the second data structure includes a statistical filter that is based upon the plurality of words.

6. The method of claim 1, wherein the first data structure, the second data structure, and the third data structure each retain words for a first time period, a second time period, and a third time period, respectively, wherein the third time period is greater than the second time period, wherein the second time period is greater than the first time period.

7. The method of claim 1, wherein the word is a phrase.

9. The computing device of claim 8, wherein transferring the word to the third data structure comprises copying the word from the second data structure to the third data structure.

11. The computing device of claim 8, wherein the word is ranked in the second data structure based upon the frequency and respective frequencies of each other word in the plurality of words.

13. The computing device of claim 12, wherein each of the first word capacity, the second word capacity, and the third word capacity are based upon a size of the computer-readable document.

14. The computing device of claim 8, wherein the word is not transferred to the second data structure upon a determination that the frequency of the word does not exceed the first predetermined limit.

16. The non-transitory computer-readable storage medium of claim 15, wherein the first data structure stores words for a first period of time, wherein the third data structure stores the words for a second period of time that is greater than the first period of time.

17. The non-transitory computer-readable storage medium of claim 15, wherein the first data structure, the second data structure, and the third data structure are independent.

18. The non-transitory computer-readable storage medium of claim 15, wherein the unique identifier is an integer.

19. The non-transitory computer-readable storage medium of claim 15, wherein each of the first data structure, the second data structure, and the third data structure are hash maps.